Avalanche Advisory for Thursday, April 10, 2014

This advisory expires at midnight.

Tuckerman Ravine has Moderate and Low avalanche danger.  Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural avalanches and human triggered avalanches are unlikely. Look out for small avalanches in isolated areas or extreme terrain.

Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when travelling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM: New Wind Slab formed high in the lee areas from snow that fell yesterday. High in the Chute, as well as just above and below the ice in the Center Bowl and Lip are where these slabs could exist in a potentially dangerous thickness. Though unlikely to bury you, they could hurt you if you triggered one and were pushed into rocks or over an ice cliff. These wind slabs could turn into Wet Slabs later. Incoming heat energy and later in the day, rain and mixed precipitation could add to instability by weakening and adding mass to the slabs. A distant third problem should still be considered. Though settlement has occurred with the recent warming trends, the steepest areas, especially those near watercourses, could heat enough to avalanche on deeper (>4′) weak layers. The top of Left Gully springs to mind due to a cornice and wind affected hang fire from earlier avalanche cycles. It is the kind of hazard that can potentially reward a person who habitually practices safe travel techniques and minimizes exposure time.

WEATHER:  Clear skies through mid-day should warm things up in the Ravines before clouds thicken and the latest round of precipitation moves in. Hermit Lake temperatures are edging towards the freezing mark from a low somewhere in the mid-twenties. Winds are currently out of the north around 40 mph and should slow further, warm and shift southwest. Later in the day they will ramp up into the 60-80 mph range on the summit  as the next cold front approaches, bringing with it another mixed bag of precipitation.

SNOWPACK:  Surface snow conditions are solidly refrozen following recent warming and last nights cold temperatures. Ambient air temperatures are predicted to rise through the day. Cloud cover will slow snowpack temperature gain so timing is everything today. NWS and MWOBs aren’t entirely in sync with the timing of incoming precipitation but my money is on some snowpack warming today as the high April sun can work pretty quickly. We are still at a crossroads with winter and spring hazards both showing their teeth depending on the time of day and quick blasts of wintry precipitation. A savvy traveller will account for this and be flexible with travel plans and pay close attention to snowpack details and changeable weather conditions and how the two play together.

OTHER HAZARDS: Slopes and gullies can change from soft and forgiving to icy and refrozen depending on subtle variations in aspect and snowpack. This can limit penetration of boots or skis therefore crampons and an ice axe are recommended for travel on steep slopes. Micro-spikes and other creeper style traction devices may be helpful on some lower angle trails, but they do not provide the security of crampons. Be prepared to handle steep, firm snow and fast, icy surfaces. Icefall can be a problem at times and though we are not into peak heating and associated icefall hazard yet, we are definitely seeing daily cycles of smaller icefall events. South facing Huntington Gullies can spawn rockfall pretty readily this time of year.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters. Posted 8:30 a.m. 4-10-2014. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2014-04-10 Print friendly